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in article , Ozzy 2005 at
wrote on 3/25/05 3:43 PM:
Just got a 5814 / 12AU7 in and tested it on my tube tester according to
the setup instructions on the tube list that comes with the tester.
Sencore Mighty Mite II, TC 114. Of course the tube was sold as NOS,
however, an odd thing happened when I tested it. Both sides fail.
There are no shorts or leakage and my tester was calibrated, albeit a
year ago, and tests all my other tubes, 12AX7, 12AT7, EL34, EL84, 6L6GC
fine and has properly indicated new and used tubes as well as shorts.
So my questions is this, might the setup data be wrong. All that
changes from a 12AX7 is the plate load goes down one click and even
testing it as a 12AX7 it only passes minimally. Could there be some
reason other than DECEPTION on the part of the seller as to why this
tube is failing. HYPE (grandiose marketing) in my book is as good as
deception. We're talking this tube has seen at least 1,000 hours to not
be in the green on my tester. That far exceeds using a tube briefly not
liking it and still claiming it's NOS.
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Here is what I wrote the seller:
Got the tube today. It was boxed very nicely and shipped promptly. The
5814 doesn't pass as per the photos of it being tested. There is no
leakage and there are no shorts so somehow this tube is testing as well
used as opposed to New Old Stock.
Any enlightenment or commentary would be appreciated. I am not the end
all know all regarding tubes and any information you can provide
regarding how you acquired it, stored it etc. might lend an explanation
to why the tube fails.
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Do I return it or do testers sometimes not tell the whole story and this
tube may very well be NOS - the getter flashing is 110% intact and thick.
Seems to me that the easiest thing to do would be to get (another) known
good 12AU7 and see what happens. I've got dozens of them if you need one.
Jon
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